A resistance random access memory using variable resistance elements is suggested. The resistance random access memory may comprise so-called cross-point type memories, in which memory cells each having a variable resistance element and a selector connected to each other in series are arranged in intersections of bit lines and word lines. Therefore, produced is an advantage that such memories are easily stacked into a three-dimensional structure so that the resultant can attain a high capacity.
The variable resistance element makes it possible to set resistance values by controlling the value of a voltage to be applied thereto, and the time for the application. The selector is a rectifier for avoiding a disturbance associated with adjacent memory cells, and may be a diode, a varistor, or some other device.
When data is rewritten in the memory cells, a voltage applied to the memory cell is distributed to the variable resistance element and the selector. The value thereof is decided in accordance with the ratio between resistance values of the variable resistance element and the selector or between capacity values thereof. When data is written therein, the voltage distributed in the variable resistance element is decreased at the moment when the set operation of the variable resistance element is finished, so that the voltage distributed to the selector is increased. As a result, most of the voltage applied to the memory cell is concentrated into the selector. When the data is erased therefrom, most of the voltage applied to the memory cell is concentrated in the selector for a predetermined time until the reset operation of the variable resistance element is finished. In short, most of the voltage applied to the memory cell when data is rewritten therein is concentrated in the selector. For this reason, the selector is required to have a resistance against high voltage. When the selector cannot endure a voltage so that a current (leakage current) penetrating through the selector increases remarkably, it becomes difficult to maintain the reliability of the selector. As a result, the selector may undergo dielectric breakdown.